Patent Document 1 and Patent Document 2 describe existing techniques related to a noncontact power transfer system.
The power transfer system described in Patent Document 1 increases the efficiency of power transfer between a card reader/writer and a noncontact-type card. Two electrodes are provided for each of the card reader/writer and the noncontact-type card. When power is transferred, the electrodes of the card reader/writer face the electrodes of the noncontact-type card in a pair to transfer electric power through capacitive coupling.
The power transfer system described in Patent Document 1 transfers electric power by forming a symmetric electric dipole, while the power transfer system described in Patent Document 2 transfers electric power through mutual electrostatic induction in such a manner that asymmetric electric dipoles are formed to face coupling electrodes to each other at a short distance.
FIG. 1 is a view that shows the basic configuration of the power transfer system described in Patent Document 2. A power transmission device includes a high-frequency high-voltage generator 1, a passive electrode 2 and an active electrode 3. A power reception device includes a high-frequency high-voltage load 5, a passive electrode 7 and an active electrode 6. Then, the active electrode 3 of the power transmission device is located in proximity to the active electrode 6 of the power reception device via a gap 4 to capacitively couple these two electrodes.
PTL 1—Japanese Unexamined Patent Application Publication No. 2005-079786
PTL 2—Pamphlet of International Publication No. 2007/107642